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| Titel |
Electrical charging of volcanic ash from Eyjafjallajökull |
| VerfasserIn |
Karen Aplin, Keri Nicoll, Isobel Houghton |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250111578
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| Publikation (Nr.) |
 EGU/EGU2015-11712.pdf |
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| Zusammenfassung |
| Electrical charging of volcanic ash is important for both the generation of lightning and the detectability and lifetime of volcanic plumes, but remains poorly understood. Previous work showed that volcanic ash samples obtained from the 2011 Gr\'{i}msv\"{o}tn eruption were readily electrically charged by friction, a process known as contact charging or triboelectrification. The efficiency of charging depended on the span, or width, of the particle size distribution, with broader charge distributions charging more than narrower or more multimodal distributions. Here we report results of laboratory experiments investigating the charging of ash from Eyjafjallaj\"{o}kull, using samples collected from S\'{o}lheimahei{\th}i, 22km from the crater, on 5 May 2010. A similar methodology to the earlier experiments with Gr\'{i}msv\"{o}tn ash was used, which involved letting small quantities of ash fall through a charge collection apparatus, and measuring the charge with a sensitive electrometer. The ash was sieved into different size bins, and artificial size distributions were also created to investigate the effect of the modality and span of the samples tested.
Like the ash from Gr\'{i}msv\"{o}tn, the Eyjafjallaj\"{o}kull ash charged more effectively when the size distribution was broader. Ash from Gr\'{i}msv\"{o}tn charged more readily, and with an opposite sign, than Eyjafjallaj\"{o}kull ash, with a median net charge of +630 pC/g compared to -116 pC/g. This difference in charging is not completely explained by the span effect described above, since the two unsieved ash samples had very similar overall spans, so would have been expected to have similar median net charges. We find that the charging may also be affected by the role of the smallest particles, |
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